When you click an item in the Scene View, Autodesk Navisworks doesn’t know what level of item to start selecting at - do you mean the whole model, or the layer, or the instance, or group, or just the geometry? The default selection resolution specifies a starting point for the object path in the Selection Tree so that Autodesk Navisworks can locate and select the item.
You can customize the default selection resolution on the Home tab 
Select & Search panel. Alternatively, you can use the Options Editor. Or you can use a quicker way, by right-clicking any item in the Selection Tree and clicking Set Selection Resolution to X, where “X” is one of the available selection resolutions.
If you find you have selected the wrong level of item, you can interactively cycle through the selection resolution, without having to go to the Options Editor or the Home tab. You can do this by holding down the SHIFT key when clicking an item. This selects an item one level more specific each time you click the item until the resolution gets to “geometry”, at which point it reverts back to “model”. Clicking on a different item reverts the selection resolution back to default (as set in the Options Editor).